I was loading out of Ewald Steel warehouse back in early 70's one day when there was a Michigan "train" in the next bay. That rig had 14 axles, double trailer setup and as I walked around it I counted 7 flat tires. I mentioned that to the driver and he said after a few more flats he would start changing them. He had more than 250,000 on but, he only run from the docks to the warehouse. No weight limit in city limits back then.